Missile with ram jet sounding device



June 3, 1958 A. R'A Azzo ETAL MISSILE WITH RAM JET SOUNDING DEVICE Filed Jan. 9, 1956 INVENTOR.

A TTORNE S Unite MISSILE wrrn RAM JET soUNmNG DEVICE Application January 9, 1956, Serial No. 558,136

7 Claims. (Cl. 46-175) This invention relates to pneumatic sound devices for use as arrowheads or other devices for operation by movement through the atmosphere.

It is an object of the invention to provide an improved sound maker operated by the pressure of a ram jet when the sound maker is moved through the air with suflicient velocity to provide the necessary pressure. The invention will be described with a whistle as the pneumatic sound maker, but it can be applied to other types of sound makers.

Another object of the invention is to provide a ram jet sounding device which is an arrowhead, and which is constructed to provide for passage of air even though the rearward end of the device is closed by the shaft of the arrow. Features of the construction provide for economical manufacture including a minimum of labor for assembly. The construction provides ram jet pressure for whistle operation with either toy arrows, or full-size arrows which move at much higher velocity than toys. The construction has the additional advantage of providing a construction requiring a minimum of alteration for use with other missile constructions.

Other objects, features and advantages of the invention will appear or be pointed out as the description proceeds.

In the drawing, forming a part hereof, in which like reference characters indicate corresponding parts in all the views;

Figure 1 is a view showing an arrow with the ram jet sounding device of this invention, and showing also a target and a bow to indicate the manner in which the invention is used; I

Figure 2 is a greatly enlarged front end view of the arrow shown in Figure 1;

Figures 3 and 4 are views, mostly in section, on the lines 3--3 and 4-4, respectively, of Figure 2; and

Figure 5 is a sectional view through a modified form of the invention.

Figure 1 shows an arrow having a head 11, a shaft 12 and a tail 13. This arrow may be shot from a how 15 at a target 16.

The construction of the arrow is shown in Figures 2-4. The arrowhead 11 is made from a sleeve which has a forward portion 15 of relatively large cross section and a rearward portion 16 of substantially smaller cross section. This rearward portion 16 fits the arrow shaft 12 and is secured to it by friction and preferably by the addition of depressions 18 formed in the wall of the sleeve and extending into the surface of the shaft 12.

Between the forward portion 15 and the rearward portion 16 there is a region 26 along which the wall of the sleeve is shaped to provide a gradual change in the cross section of the sleeve. There is a groove 22 in the inside surface of the forward portion 15 of the sleeve near the juncture of this forward portion 15 and the region 20. A pneumatic sound maker 26 forms a partition across the sleeve and is held in place by the groove 22. In the illustrated construction, the sound maker 26 constitutes the rates atent Patented June 3, 1958 maker is representative of partitions and that the con struction may be such that the sound maker forms only a part of the partition. There are openings 28 for the passage of air through the sound maker 26 for operating the sound maker, and the purpose of partitioning the sleeve is to build up a ram jet pressure in the forward portion 15 for blowing operating air through the openings in the sound maker.

The sound maker 26 is a whistle formed by two confronting dished elements 31 and 32 which enclose a chamber between them. The peripheral edge portions of the dished elements 31 and 32 are secured together in a circumferential seam around the whistle and this scam extends into the groove 22. Such whistle construction is conventional.

The length of the forward portion 15 of the sleeve must be proportioned to the sound maker so as to provide the required ram jet pressure. Greater pressure is obtained by making the forward portion 15 longer. The velocity with which the sleeve will move is another consideration.

I Shorter sleeve lengths are suitable for missiles moving at higher velocities.

If a sound maker of the vibrating reed type is used, a much greater latitude of operating pressure is permissible than with whistles of the type disclosed in Figure 3. Such a whistle requires pressure within a fairly limited range and will not operate satisfactorily either below or above this range of pressure. By way of illustration, a whistle having a diameter of .75 inch and a front-toback length of 0.25 inch with openings of 0.19 inch, a forward sleeve length of two inches ahead of the whistle gives satisfactory operation with either toy bows or fullsize bows used to shoot the arrow. The higher velocity with a full-size bow gives the whistle a somewhat higher pitch but the operation is completely satisfactory. This example is for an un-pointed arrowhead, that is, one in which the forward end of the sleeve is unobstructed. With pointed heads and constructions such as that which will be described, it is not necessary to increase the length of the cylindrical portion of the sleeve ahead of the sound maker unless the points are made very large so that they ofier an excessive amount of obstruction to the entrance of air into the sleeve.

The arrow shaft 16 closes the rearward end of the sleeve and openings 36 are provided through the side of the sleeve for the escape of air behind the sound maker 26. These openings are located in the side wall of the sleeve along the region 20. This location has several advantages. One is that the openings 36 are more in line with the air coming from the sound maker so that there is little back pressure resulting from a required change in the direction of flow. A more important advantage is that the reduction in cross section of the arrowhead produces an aspirator action as the arrow travels through the air and thus obtains a suction for withdrawing air from within the sleeve through the openings 36. This suction behind the sound maker reduces the necessary length of the forward portion 15 in which the ram jet pressure is built up.

The arrowhead may be provided with a point by extending the wall of the forward portion 15 forwardly around limited arcs of the circumference of the sleeve. Two such extensions 4-]. and 42 are shown in Figures 2-4 and these extensions converge to form the arrow point. When the invention is used with toy arrows, the point is omitted for greater safety. Even when used for target practice, the location at which the arrow strikes the target can be observed, even though the arrow does not penetrate the target and remain in place.

Figure 5 shows a modified form of the invention in which the sleeve is connected to a bracket 50, preferably a band extending around the sleeve and gripping the sleeve by spring pressure. Parts of the construction 7 shown in Figure which are the same as that shown in:Figures 2-4 are indicated by' the same reference characters as in Figures 2-4. The rearward end of the sleeve circle to obtain the air velocity required for operating the whistle.

Tail fins on the back of the plug'52 hold the sleeve with its open end forward.

The preferred embodiments of the invention have been illustrated and described but changes and modifications can be made and some features can-be'used in different combinations without departing from the inven tion as defined in the claims.

What is claimed is:

l. A ram jet sounding device comprising a sleeve/having a portion of its length toward its rearward end of reduced cross section and having a forward portion of larger cross section and a region along which the side wall of the sleeve converges toward the rearward portion of the sleeve at an acute angle to the longitudinal anis' of the sleeve, a pneumatic sound maker located in the sleeve at a substantial distance back from the forward :end of the sleeve andthaving a passage through which air travels through the sound makerrfrorn the forward portion of the sleeve to the region Where the sides converge; the

length of the sleeve wall ahead of the sound rnakenbeing imperforate and the sleeve Wall behind the 'sound'maker having one or more openings therethrough of a total cross section substantially larger than the air passage through the sound maker, said opening through the wall of the sleeve being located in the converging portion of the sleeve wall and facing in a'directionwith Ea substantial rearward component whereby forward movement of the sleeve in the direction of its longitudinal-axis causes an aspirator suction. for drawing additional air through the sleeve and sound maker. a

2. The ramw jet sounding device described in' claim 1 and in which the sleeve is of substantially circularicross section with a circumferential groove in its insideLface at the location of the sound maker, and in which the sound maker is a whistle made .of dishedlelementsconfronting one another toenclose a chamber between them with openings through the elements providing the air passage of the Whistle, the'dished elements being connected together around their peripheral edges and being held at their peripheral edges in said groove.

3. The ram jet sounding device described inclaim 1 and in which the interior of the sleeve is partitioned "off at a location adjacent to the juncture of therearward end of the larger diameter portion of thesleeve-and'the forward end of the converging region of the sidewalL-at least a portion of the partitioningof the sleeve being done by the sound maker so that the air pressure builtiup in the forward portion of the sleeve, during movement through the air, develops pressure available for moving air through the sound maker to operate said. sound maker. 4. The ram jet sounding device described in claim 1,

and in which the sleeve has a bell mouth at its forward end of greater diameter than the rest of the sleeve, a portion of generally cylindrical cross section rearward of the bell mouth, a rearwardsection .of progressively decreasing cross section, with one or more openings therethrough for 'escape ofiair from the sleeve, an'da whistleextending across the sleeve intermediate the bell mouth and. said rearward section.

5. A ram jet sounding'd'evice comprising'an arrowhead having a sleeve with its rearward portion'of smaller cross section'than its forward portion, and having aninterrnediate region of its lengthrconverging rearwardly to provide a gradual change from one cross section to the other, an

arrow shaft with its forward end extending into the rearward reduced cross section of the arrowhead and closing the rearward end. of the sleeve, apoint atithe arrowhead with openings therein for xadrnittingair into :the sleeve,-a pneumatic sound makerlocated in the :sleeve at a-substantialdistance baclcfrom the: forward end, means securing the sound maker: in positionin the sleeve, the sound maker having an opening for'thef'passage of its operating air in the direction of the length'iofthe sleeve, and the sleeve having one or more openings throug'h its sidewall between the sound maker and theforwardend of the arrow shaft.

'6. TheJra-rn jet sounding'device described inclaim 5 and in whichthe sleeve is of circular .crossse'ctionandjthe' point at the'front of-the arrowhead is formed-by portions of thefrontiedge of the sleeve projecting forwardly for difierent distances atv angularly spacedlocations around the sleeve and around limited arcs oflthesleeve circumference, at-least some'of said portions of the front edge convergingtoward one another in a forwardly extending direction'to form the point.

. 7. The ram jet sounding device described in claim 5 and in which-the sleeve is of circular cross section and has a .grooveinits inside surface at' the location of 'the sound-maker, and the sound makerisa whistlemade of confronting dished elements enclosing a chamber and with openings through the dished-elements for the passage-of air, the peripheral edges of the dished elements 7 being connected together and fitting within the groove of the sleeve,'iand thepoint' of thearrowhe'adbeing formed by portions .of the frout'edgelof the sleeve projectingfor wa'rdly :for different distances at .angularly spaced locations around the sleeve and around limited arcs cf-fthe sleeve'circumference, at least some ofsaidi portions of the front edge converging together to form the point at'their forward ends; 7

.Re'fereucesCited in the file of this patent UNITEDvS 'l-ATES PATENTS- Reaben Jan.- 27, 1920 

